The invention relates to an apparatus for the dimensionally accurate cutting of a product carrier which is in the form of a strip, is transported further in a cyclic or continuous manner in the longitudinal direction and has cells which are arranged one behind the other, are sealed in an airtight manner and in which sensitive products are packaged. An apparatus of this type fundamentally comprises a rotating cutter roller, which severs the product carrier in each case in the region of a sealing web which is situated between two cells, is arranged transversely with respect to the longitudinal direction and is provided with a lattice-like embossing.
Sensitive products should in this case be understood to mean solid, pasty or liquid products which are sensitive with regard to drying out or the ingress of moisture or else with regard to their sterility (contamination by microorganisms). Typical products in the foodstuffs industry are, for example, mustard, mayonnaise or ketchup, and typical products in the pharmaceutical industry are tablets, including sugar-coated tablets, skin gels or ointments.
Packaging for moisture-sensitive pharmaceutical preparations in tablet form frequently uses foil and film which are sealed closed around the tablets; that is to say each tablet is situated in a cell which is sealed in an airtight manner and is bounded all around on the outside by sealing seams. As a rule, a plurality of sealed tablets, for example two or four, are accommodated in one package unit in the form of a strip. Aluminium foil composites are particularly suitable as packaging material. In order to use the medicament, a strip unit with tablets is removed from the supply pack and the foil is torn open in the vicinity of a tablet, so that the tablet is available. The sealing machine, in production mode, provides the tablets such that they are sealed in in an airtight manner on a foil/film-type tablet carrier, in which each tablet is enclosed in a square by two longitudinal sealing webs and two transverse sealing webs. The longitudinal sealing webs are arranged parallel to the edges of the foil/film carrier and the transverse sealing webs are arranged perpendicularly thereto. During fabrication and automatic packaging, the tablet carrier is then cut off in each case in the region of a transverse sealing web, thereby producing smaller package units in strip form and each having two or four tablets, for example, which units are then packed ready for sale in a box of 10 to 40 units.
The cutting-off apparatus that is usually employed is a rotating cutter roller, which is in a fixed cycle ratio with the preceding sealing roller, in order that the separating cut is made in each case as exactly as possible (.+-.1 mm) in the centre of a transverse sealing web. However, it has been shown in operational practice that the tolerances of the sealing seams or webs in the longitudinal direction are so large, on account of length fluctuations of the foil/film-type tablet carrier, that it is not possible to achieve the accuracy demanded above. Such fluctuations are to be attributed to the fact that in the course of production, the tablet carrier is alternately accelerated and braked and, consequently, exposed to great mechanical stresses. The resultant inaccuracy in the separating cut has the effect that in unfavourable cases the transverse sealing web is cut at the edge or even outside the web width and the requisite reliably tight sealing-in of the tablets is no longer ensured. In these cases, air and/or moisture can penetrate and the storage life of the tablets is greatly reduced. In the worst case scenario, it is even necessary to block entire batches.